ML19340F199
| ML19340F199 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 01/10/1981 |
| From: | Steingart K PHYSICIANS FOR SOCIAL RESPONSIBILITY |
| To: | Godard D Office of Nuclear Reactor Regulation, OREGON, STATE OF |
| References | |
| NUDOCS 8101210318 | |
| Download: ML19340F199 (19) | |
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r VOLCANIC HAZARD TO TROJAN NUCLEAR POWER PLANT A
SUMMARY
The Trojan Final Safety Analysis concludes that Mount St.
Helens is dormant.
This safety analysis also asserts that the Trojan Nuclear Power Plant will not be seriously affected by any large volcanic eruption.
On this basis, Trojan is sited within 34 miles of the volcano.
Last year Mount St. Helens exploded the dormancy conclusion of the Final Safety Analysis.
Public safety now relies on the accuracy.of the analysis of the effects of a large eruption.
But how confident can the public be in this analysis?
To find out the Portland chapter of Physicians for Social Responsibility (PSR) asked Norman Buske, a physicist who evaluates environmental hazards, to review the analysis of volcanic risk to Trojan.
His review revealed two major errors in the Trojan Final Safety Analysis.
That analysis equated the a-ncient volcanic eruption which produced Crater Lake to the worst potential eruption of Mount St. Helens.
The Crater Lake eruption was treated in the analysis as though it had occurred at Mount St. Helens.
In this treatment, the analysis failed to orient the ash fall toward Trojan.
That orientation is required for the worst case eruption.
Thus, the potential ash fall at Trojan was underestimated by a factor of at least 20.
Furthermore, the treatment neglected pyroclastic flows altogether.
During the Crater Lake eruption, one of these
" glowing ash avalanches" swept 40 miles down the valley of the Rogue River, on the west side of the volcano.
The valley was devastated.
The Kalama River valley extends westward from Mount St. Helens to the Columbia River, 33 miles away.
Trojan is sited on the bank of the Columbia, opposite the Kalama River mouth.
Thus, Trojan is subject to potential pyroclastic flows from a Mount St. Helens eruption.
Risks of these volcanic events were evaluated in the review.
It was found that Mount St. Helens imposes a risk of failure on Trojan over 100 times the accepted risk of failure for all United States nuclear power plants.
January 1, 1981
S E A R C H F "c" SE"ces RO BOX 14209 5 October 1980 PORTLAND OREGON 97214 EVALUATION OF DESIGN HAZARDS OF AIRBORNE ASH AND FYR0 CLASTIC FLOW FOR THE TROJAN POWER PLANT SITE.
Physicians for Social Responsibility (PSR)
Prepared for SEARCH 0312
SUMMARY
With renewed activity of Mount St. Helens, possible volcanic hazards to the Trojan Nuclear Power Plant are of interest for public safety. The original Trojan safety analyses for airborne ash and pyroclastic flows are evaluated here. For this evaluation, a regional approach, similar to that enployed previously, is used. This evaluation reveals major systematic errors in the original safety analysis.
In particular, the volcano was assumed dormant or harmless during the life of the plant. The effect of wind on ash fall was misapplied to the design condition. The effects of blast were ignored. Pyroclastic flows were casually dismissed. The present evaluation presents a preliminary correction of these errors.
The close proximity of Trojan to the most dangerously active volcano in the conterminous United States is found to impose severe design conditions for both airborne ash and pyroclastic flows--the only volcanic conditions evaluated herein. Preliminary design conditions are found to exceed 16 feet of dry ash or 8 feet of wet ash, resulting from a sudden ash fall.
Pyroclastic flows are also found to present a significant design condition because of the 34-mile proximity of Trojan to the volcano and because of the connecting path provided by the Kalama River Valley.
AIRBORNE ASH AND PYROCLASTIC FLOW 5 October 1980 prepared for:
PSR SEARCH 0312 PAGE TWO BACKGROURD TO THIS EVALUATION This report summarizes the results and conclusions of an evaluation of volcanic hazards for the Trojan Nuclear Power Plant site, one mile south of Prescott, Oregon.
SEARCH Technical Services selected ash fall and pyroclastic flow for evaluation because of the potential dangers to the plant and because of the relative simplicity of the analysis required for review. Other volcanic hazards are possible.
Norman Buske, a physicist, conducted this evaluation between 16 September and 5 October 1980. He was assisted by Lee Kirkpatrick and Linda Josephson.
The principal investigator has B.A. and M.S. degrees in physics and an M. A. degree in earth and planetary sciences. He has 12 years experience in the prediction and evaluation of environmental disasters and design conditions. He has conducted this work for electric utilities (conventional and nuclear), the U.S. Navy, the petroleum industry, coastal developers, and others, at about 30 sites, worldwide.
TROJAN SITE Trojan is located on a 635 acre site, on the west bank of the Columbia River estuary, about 42 feet above the high water level. The Kalama River enters the Columbia River on the east bank, opposite the Trojan site. The head of the Kalama River is on Mount St. Helens, 34 miles ENE of Trojan. Figure l shows the Trojan site and its location.
ENVIRONMENTAL DESIGN CRITERIA Design criteria for nuclear power plants are established by the Nuclear Regulatory Commission (NRC) so that "the facility can be operated without undue risk to the health and safety of the public" [Part 50, 1980, p.27]. These design criteria are required to reflect Appropriate consideration of the most severe of the natural phenomena that have been historically reported for the site and surrounding area, with suf ficient margin for the limited accuracy, quantity and period of time in which the historical data have been accumulated...[ emphasis added, p. 28].
The present evaluation of volcanic hazards of Mount St. Helens for the Trojan site is, in effect, an appraisal of the relationship between environmental events and amiae risk to the health and safety of the public.
As a starting point, a definition of risk is necessary:
For this evaluation, risk is the chance that some important facility design condition will be
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PSR 5 October 1980 SEARCH 0312 PAGE THREE TROJAN SITE LOCATION
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AIRBORNE ASH AND PYROCLASTIC FLOW 5 October 1980 prepared for:
PSR SEARCH 0312 PAGE FOUR exceeded in a specified period of time--usually one year.
Next, the meaning of "andue risk to the public" is considered.
This is basically a matter of choosing an acceptable value of risk. One possible value is suggested by the Atomic Energy Comission's Reactor Safety Study, as described in the reprint, " Nuclear Reactors: How Dangerous?" [ Reader's Digest, R.E. Lapp, April 1975]. This reprint cites a one in 100,000,000 per year chance of serious escape of radioactivity from any single reactor.
That is a very low risk.
In fact, it appears to be lower than may be needed to assure public safety. This may be seen by considering the number of nuclear power plants (55 in 1975), the length of time during which no major accidents would be acceptable (say, a 200-year life for the present nuclear industry), a safety factor (say,10), and the number (say,10) of more or less unrelated kinds of events which expose a plant to risk of failure. Multiplying these factors, one obtains an acceptable risk of about one in 1,000,000 per year for any single kind of event.
In order to assess such small risks, one must go.beyond the plant area and consider the worst condi?. ions recorded in the region--just as the NRC requires. This record includes geologic information.
As a starting point for the evaluation, one turns to Potential Hazards from Future Eruptions of Mount St. Helens Volcano, Washington
[G.S. Bull.1383-C,1978, p. Cl], which states that the volcano is a serious hazard based on its past history of spasmodic explosive behavior including lava flows, pumice falls, pyroclastic flows, and mud flows. A quick look at the historic record shows that:
Mount St. Helens has been more active and more explosive during the last a,500 years than any other volcaro in the conterminous United States [ ibid.].
This activity is outlined in Table 1.
Geological Survey Bulletin 1383-C provides a basis for evaluating volcanic hazards which are " expectable" [ title D.].
Thus, the Survey only considers risks greater than about one in 3000 per year [p. C-19].
But a nuclear power plant nust be designed to survive potential hazards, as well as expectable hazards.
In order to assure that the public will not be exposed to a release of radioactivity, one must evaluate risks far smaller than those considered by the Survey. This difference is quantifiable as follows:
hazards attendant risks expectable s one in 2,000 to 3,000 per year
% one in 1,000,000 per year potential Attention now turns to the ash fall hazard.
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PSR 5 October 1980 SEARCH 0312 PAGE FIVE ERUPTIONS AND DORMANT INTERVALS AT MT. ST._ HEL_ENSINCE.500 B.C.
A.D.
1980--Tephra eruptions 1900--Dormant interval of 123 years 1857--Last recorded pyroclastic eruptions
--Eruptions of pyroclastics, domes, lava flows 1800--Pyroclastic eruptions (T), mudflows
--Apparent dormant interval of ca.150 years 1700--
--Pyroclastic flows (avalanches)
--Dome eruptions, mudflows 1600--
--Apparent dormant interval of ca.100 years 1500--Airborne pyroclastic eruptions (W), pyroclastic flows
--Pyroclastic flow 1400--Lava flows, pyroclastic flow
--Pyroclastic flows 1300--Dome eruptions (?)
1200--
1100--Apparent dormant interval of 400-500 years 1000--
900--
--Airborne pyroclastic eruption 800--
700--
600--Apparent dormant int'erval of 400-500 years 500--
400--
--Airborne pyroclastic eruptions, mudflows 300--
A.D.
200--Airborne pyroclastic eruptions 100--Lava flows-0--
--Pyroclastice flows, mudflows 100--
B.C.
--Pyroclastic flows 200--
300--Pyroclastic flows, airborne pyroclastic eruptions 400--Airborne pyroclastic eruptions, mudflows
--Lava flows 500--Apparent dormant interval, 400-500 years Chronology indicates knoun eruptions.
TABLE 1.
l Taken from:
Fire and Ice, Stephen L. Harris,1980, p.174-175.
AIRBORNE ASH AND PYROCLASTIC FLOW 5 October 1980 prepared for:
PSR SEARCH 0312 PAGE SIX
+
ASH FALL In the following discussion, no distinction is made between " pumice",
" ash", and "tephra" fall s.
They all describe deposition of erupted materials which were carried by the air.
Data from the 18 May 1980 Mount St. Helens eruption indicate that first rains compact freshly fallen ash to about half its original depth
[" Areal Distribution, Thickness, and Volume of Downwind Ash from the May 18, 1980 Eruption of Mount St. Helens," U.S.G.S Open File Report 80-1078, A.M. Sarna-Wojcicki, Fig. 3]. Thus, as a conservative approximation, the present thickness of old tephra deposits is assumed to be one-half the thickness of the original uncompacted tephra fall.
MOUNT ST. HELENS Five severe ash falls from Mount St. Helens are outlined in Fig. 2.
Because of the strong winds present during the 18 fiay 1980 eruption, that ash fall was too thin and widely distributed to include in this map
[ Sarna-Wojcicki, Fig. 3 and p. 7 and Bull.1383-C, p. C17]. Referring to Fig. 2, layer "Yn" is seen to be the most severe ash fall recorded. The compacted ash from that event is 3 feet deep 24 miles north of the volcano [ Pumice and Pumicite Occurrences of Washington, State Div. of Mines and Geology Rept. No.15, W. Carithers,1945, p. 20] and 18 inches deep on Mt. Rainier 50 miles away [fiount St. Helens, The Volcano of Our Times, D. and O. Roberts, 1980, p. 4].
With only a 4500-year geologic record of recent Mount St. Helens activity, it is appropriate to turn to other nearby Cascade volcanoes to evaluate the worst that may reasonably be anticipated. For a full appraisal, one would conduct a detailed study of ash falls from all the Cascade volcanoes. However, in the Trojan Final Safety Analysis Report (FSAR),
the Mt. Mazama eruption of some 6600 years ago was selected for use as the worst-case condition [p. 2.5-4] on the basis of the size of the eruption.
With the reservation that the biggest blast does not necessarily produce the deepest ash, that selection is followed here.
MT. MAZAMA Crater Lake lies about 210 miles south of Mount St. Helens. This lake was formed af ter an eruption of Mt. Mazama--the parent volcano--some 6600 years ago. That eruption is generally considered to be large by recent Cascade volcano standards.
The Mt. Mazama eruption was carefully studied by Howel Williams.
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PSR 5 October 1980 SEARCH 0212 PAGE SEVEN MT. ST. HELENS TEPHRA DEPOSITS
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AIRBORNE ASH AND PYROCLASTIC' FLOW 5 October 1980 prepared for:
PSR SEARCH 0312 PAGE EIGHT His Geology of Crater Lake Natinnal Park, Oregon [ Carnegie Inst. of Wash.
Publ. 540,1942j is still considered authoritative concerning pumice falls and pyroclastic flows from the Mt. Mazama eruption.
Williams' map of ash fall depths and pyroclastic flow distributions appears as Fig. 3.
This shows that the main lobe of the Mt. Mazama ash fall was to the NNE, reflecting wind conditions at the time of the eruption.
The pumice fell in the typical downwind direction from Crater Lake and left compacted deposits 3 feet thick as far as 67 miles away.
APPLICATION TO THE TROJAN SITE The Mt. Mazama tephra fall event may be applied to the Trojan site (as in the FSAR, p. 2.5-38) by superpositioning the ash origin onto the location of Mount St. Helens and taking into account the site location to the WSW of the origin.
In analyzing the possible impact on Trojan of ash fall from such an eruption of Mount St. Helens, possible future blast directions as well as variations in wind speed and direction must be considered. This the FSAR failed to do.
Close to a volcano, the extent of ash fall depends en the details of the eruption as well as the wind [ Bull.1383-C, p. C-10].
In the 18 May eruption of Mount St. Helens, the blast zone extended at least 50 miles Figs. 4 and 5b]gh the atmosphere from the volcano [ Sarna-Wojcicki, p. 5 and laterally throu There seems to be no justification for assuming that future blasts during the 40-year life of the Trojan plant will all be from the north side.
- Indeed, Future tephra eruptions are possible from vents on any flank of Mount St. Helens, as well as from the summit, and thus any part of the volcano can be af f ected [ Bull.1383-C, p. C-10].
Similarly, wind speed and direction in the area must be considered to be variable. During the fall, winter and spring seasons, winds are dominantly toward the northeast. However, during the sumer season, Over extreme scuthwestern Washington and most of Oregon an anticyclonic cell, with sinking air-flow is found [ Atlas of the Pacific Northwest, 6th ed., R. M. Highsmith, Jr., and A.J. Kimerling, eds.,1979, p. 45].
This is shown in Fig. 4.
This wind pattern brought a sprinkling of ash to Portland and the Trojan site last sumer, following very small erupt. ions of Mount St. Helens.
The effect of low wind speed is to increase the depth of ash accumulation close to the volcano and to decrease the ash depth far from the volcano [see Sarna-Wojcicki, p. 5].
If winds do not carry the erupted ash away from the SEARCH.
pr pared for:
PSR 5 Octob:r 1980 SEARCH 0312 PAGE NINE CONT 0UM.(F.EET)0F_MT.MAZAMATEPHRAFALL AND EXTENT OF PYROCLASTIC FLOWS.
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PSR 5 October 1980 SEARCH
- 0312 PAGE TEN AVERAGE SUMMER WINDFLOW FOR THE PACIFIC NORTHWEST
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AIRBORNE ASH AND PYROCLASTIC FLOW 5 October 1980 prepared for:
PSR SEARCH 0312 PAGE ELEVEN volcano, more of the ash will fall nearer to the volcano.
Clearly, there is a reasonable chance of ash being carried by wind toward the Trojan site. However, the worst-case ash fall situation appears to oe: A west-flank blast occurring with winds directed toward the east. This could produce local air stagnation and heavy ash deposition in the vicinity of Trojan.
On the basis of the possibilities of either easterly winds, calms, or a west-flank blast with winds toward the east, the probability of major deposition at Trojan, assuming that a major Mount St. Helens ash eruption has occurred, is considered to be at least 20 percent.
With this probability in mind, the Mt. Mazama eruption data can be superpositioned over Mount St. Helens, with the major lobe directed roughly toward the Trojan site, Fig. 5.
This gives an idea of the potential ash fall at site from a severe eruption of Mount St. Helens.
The result:
Abot.t 8 feet of compacted ash at site. The initial fall of uncompacted ash would probably be at least twice this deep--16 feet.
From the above considerations, the present risk of a Mt. Mazama-class ash eruption from Mount St. Helens is proposed to be about one in 10,000 per year--roughly the length of record. W1.th an estimated 20 percent chance of this deposit:en being directed toward site, the risk of an uncompacted ash fall of 16 feet at Trojan site is estimated to be one in 50,000 per year.
PYROCLASTIC_ELOR For this evaluation, no distinction is nade between the terms
" pumice flow", " ash flow", "pyroclastic flow", "nuse ardente", and " glowing avalanche". They all describe an eruption of hot tephra-filled gas, whin sweeps down the side of a volcano, of ten following river valleys.
MOUNT ST. HELENS Pyroclastic flows are typical of Mount St. Helens eruptions, particularly late in the eruptive cycle [" Eruptive Sequence at Mount St.
Helens, Washington," Geol. Abs. with Programs, 3_(2), C. A. Hopson,1971, p.138]. Even in the primarily airborne ash eruption of 18 May, Mount St.
Helens produced pyroclastic flows:
Traveling at a speed of 100 miles per hour and heated to 800*F., each glowing avalanche melted snow, singed trees, and cremated overy smaller life form in its brimstone path
[ Roberts, p. 6].
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PSR 5 October 1980 SEARCH 0312 PAGE TWELVE POTENTIAL ASH FALL DEPTHS AND DISTRIBUTION FOR MT, ST. HELENS C t,c p i a
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FIGURE 5 snaced areas are f or cep ens greater tnan 3-f eet, 5-feet, and io-feet.
Depth at Trojan s i te i s abou t 8-f eet, compacted ash.
Crater Lake isopachs taken from: Geology of Crater Lake National Park, Oregon, Howel Williams,1942, p. 70.
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AIRBORflE ASH AND PYROCLASTIC FLOW 5 October 1980 prepared for:
PSR SEARCH 0312 PAGE THIRTEEN More generally, Ouring the past 600 years " hurricanes" of incandescent debris repeatedly raced down the volcano's slopes and moved down valleys within a 10-mile radius of the cone [ Fire and Ice, S.L. Harris,1980, p.172].
The Kalama is one such river valley. From its source on flount St.
Helens, it empties into the Columbia directly across from the Trojan site, 34 straight-line miles from the old sumit.
While the 4500-year geologic record for the influence of Mount St.
Helens on the Kalama River shows little or no evidence of pyroclastic flows [ Bull.1383-C, Plate 1], one must again turn to the region to estima the risks required for nuclear power plant design. Following the FSAR usu of the Mt. Mazama eruption to develop volcanic design conditions, attention is again directed to that 6600-year old eruption.
MT. MAZAf1A Williams found recains of several pyroclastic flows, one of which traveled 40 miles down the Rogue River Valley, 35 straight-line miles from the source, Fig. 3.
At the end of this flow he found charred logs up to 3 feet in diameter [p. 83], evidence of the extreme heat experienced that far from the source.
In considering the possibility of a pyroclastic flow down the Kalama River Valley to the Trojan site, one might imagine that the Columbia River would provide some protection. This may not be the case, as illustrated by the following description of the northern pyrociastic flow from the Mt.
Mazama eruption:
Another seething hurricane of pumice and rock fragments descended to the north, sweeping across Diamond Lake and emptying a load of pumice bombs into the valley of the North Umpqua [ Harris, p. 95].
The Diamond Lake crossing was apparently about 3 miles long, and the tenninus of this flow was 15 or 20 miles beyond. Clearly, water is no barrier to pyroclastic flows.
If the Mt. Mazama pyroclastic flow distribution is $3perpositioned onto Mount St. Helens, with the Kalama River Valley (Fig.1) substituted for the Rogue (Fig. 3), it appears that pyroclastic flows can potentially reach the Trojan site. The risk of this ever,t is estimated to be about one in 10,000 per year on the basis of the length of record and Mount St. Helens' activity.
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AIRBORNE ASH AND PYROCLASTIC FLOW 5 October 1980 prepared for:
PSR SEARCH 0312 PAGE FOURTEEN REVIEW 0F TROJAN SAFETY ANALYSIS The following items have been reviewac as part of the present evaluation:
(1) FSAR Section 2.5, Geology and Seismology.
(2) Richard B. McMullen affidavit of 12 April 1978, Docket 50-344, " Proposed Amendment to Facility Operating L ' cense...."
(3) Energy Facility Siting Council (EFSC) letter of 14 July 1960 to PSR.
(4) EFSC response of 11 September 1980 to PSR.
In brief, these references incorrectly consider Mount St. Helens to be dormant or of no quantifiable hazard. The effect of wind on ash fall is evaluated incorrectly, and the direct and indirect effects of blast are totally ignored.
Pyroclastic flows are casually and incorrectly dismissed because of the distance and topography involved.
Rather than dwell on the individual errors of the Trojan Safety Analysis, it appears more productive to consider the nature of these errors. The key appears to lie within the following statement:
The only item with a frequency w]ithin the working life of the plant (about 40 yr) are [ sic ffoods and debris flows with an indicated possible frecuency of once in 10 yr to once in 100 yr.
There is [ sic), as yet, no published data for possible frequencies of volcanic events at Mount St.
Helens...[FSAR,2.5-38].
From this one sees that the Safety Analysis only considered events with risks not much less tr.an one in 40 per year.
The error in this approach is obvious if,,ne considers several, unrelated design events. Suppose that a plant is subject to 10 such events, each having a risk of only one in 200 per year. Thus, each event has a frequency far outside the 40-year life of the plant. The overall risk to the plant is calculated as follows:
1 - [(1-1/200yr)"]* = 0.87 per 40-yr life.
That is, the plant would have an 87 percent chance of failing.
(If this approach was followed in other parts of the safety analysis (not evaluated here), it is obvious that the plant may be subject to extraordinary risk of failure. This possibility should be brought to the attention of the EFSC immediately.)
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- SEARCH,
AIRBORNE ASH AND PYROCLASTIC FLOW 5 October 1980 prepared for:
PSR SEARCH 0312 PAGE FIFTEEN From this incorrect approach follow the incorrect conclusions of the FSAR concerning the hazards of airborne ash fall and pyroclastic flows.
CONCLUSIONS BASED _QN THIS EVALUATION, FOR A NUCLEAR POWER PLANT:
[1] Trojan site should probably have design depths for ash fall in
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excess of 16 feet for fresh, dry ash or 8 feet of wet ash. This design depth appli.es directly to design loading of structures and indirectly to plant operations and functions.
[2] Pyroclastic flows should probably be included as a plant design condition. This design condition implies criteria of temperature, wind, erosion and impact, and loading. These criteria apply to structures and to plant operations and functions.
[3] The Trojan Final Safety Analysis shows no comprehension of the analysis or design required to assure safe plant operation.
Thus, there is no apparent, present basis to assure safe operation of the facility.
Submitted by, Norman Buske Principal Investigator
///
- SEARCH,
A This is what the TROJAN FINAL SAFETY ANALYSIS REPORT (page 2.5-4) says about warning of volcanic eruption:
0F CONSIDERABLE IMPORTANCE FROM A SAFETY STANDPOINT, SHOULD VOLCANIC ACTIVITY INCREASE IN THE CASCADES, IS
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THE USUAL FAIRLY LENGTHY WARNING PERIOD INDICATING RENEWED VOLCANIC ACTIVITY.
FEW IF ANY VOLCANIC ERUPTIONS HAVE NOT BEEN PRECEDED BY EITHER THERMAL CHANGES, INCREASED ti!NOR SEISMIC ACTIVITY, SWELLING OF THE GROUND FROM INTEF,NAL PRESSURE, SMALL EMISSIONS OF STEAM OR ASH, OR OTHER SIGNS.
IN THE UNLIKELY EVENT THAT FUTURE ACTIVITY DOES INDICATE THAT A RISK TO THE PLANT'IS DEVELOPING, ACTION CAN EASILY BE TAKEN TO ELIMINATE ANY RISK TO PEOPLE IN THE AREA.
So far, Mount St. Helens has provided all of these listed signs of renewed volcanic activity. The scientists have now given notice (see story, other side) that this is all thewarning that can be expected.
With a 100 mile-per-hour travel speed, a pyroclastic flow from Mount St.
Helens, down the Kalama River valley, would reach Trojan in less than half an hour.
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ching 100 mph, capaby of burning If the magma has thanged, and the ford Pinchot National Fcrest said a By JOHN $NELL l
the bark from trees as thypasa.
new magma does not release lis pent.up meeting has been called for Jan. It to J
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~ ho."The (Geological Survey)is telling gases as easily as before, the mountain consider reducing the boundarles of the
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' Innt-t se may be more explosive, just as a fully. Forest Service Red Zone.
l Scientists said Monday 1 ofthe'/ fulf" people on the ground. *Be care-
' %' '*E.4 ' P' said U.S. Forest Service spokes-corked ch mpagne bottle blows its oork er could give advance war farther and more violently than a bottle Gene Smith, acting chts! of sales for t.9 -
next violent erupilon of at SilicI/ ;oanTomCorcbras.'
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..A the fusest, said seven timber sales on
[ T. '."1*[f;.gni. whWollicials from the statt of * * "They're;asying'It's not going to g
i with a slow leak.
n ust the volcano have been W Washington and the 'l S. Forest Service givi A whole lot of notl(e. so these peo-Ms. Cashman said it is also possible p ned because of restrictions on allow.
P-announced they wot.ld consider allow.. plc are la peril." he said. "When it gs that the magma underneath the moun-
N. s..."f i ine, loggers to work closer to the vol ' dangerous,_l{ could get rea'l dangerous tain no longer has much gas in it, and is.
Ing loggers into the area.
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[tal fast,".. k. earlier believed they
. Q,,k., jolutly by the U.S. Get,togical Survey, therefore. lcu explosive then before.
Wash!ngton Department of Emer-cano.
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A precautionary statemtet. Issued,, Scientist flob Norris. a spokesman for the gency Services operations supervisor would be able to give a two-or three" University of Washington's 6cismic re-Dave Guier said Monday snat the state
' Ca... and the selsmk research center at tha hour warning of an lmpending eruption. search tenter.salJ the Monday advisory Hed Zone, which covers private land
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University of Washington in Seattle.
- Geological Survey spokeswoman was twurd I,..aud violent and unpre-west and north of the crater, also may p'.
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said that the snountain is unpredictable Kathy Cashman said Monday that the
.g;, table eruptions "are associated wit'h be redrawn.
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and. "Eatra caution should be taken recent growth of the lesa dome and the Lt e growitMilavd domes "
"Af ter (Gov. elect John) Spellspan t
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near the volcano.
relative seismic Inactislly on the moun-N
'. I. ', i" E The statement also said that recent tain show that the volcano "Is in a dif-N""I* "id that the lava dome could takes of fice Jan.14, we wn!I take anoth-J
seismic activity, coupled with' the ferent manifestation of what we nor-sesve as a plug in the crater that would er look,, Guier said. "If the mountain
' '.C.U growth of a triple sphered lava dome mally see. People aren't sure what it '8.use pressure to build insiJe the moun. remains as quiet as it has been, there is
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a strong possibihty of seducing the size luside the crater. has led scientlata "to means.
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speculate that if a tarte ash efoud'or "The whole form of the lava move-Itather than blast the dome apart.
- .;. pyro (lastic flow were to take place. It ment has changed, and we raay not get tio.rrh said. a future eruption mig Any future zone changes are pri-p.lgv occur with little or no forewarn-the warning w e've expe. led," she said.
blow from un.terneath the dorpdrLa marily expc<ted to benefit loggmg m-jag,"
Ms. Cashman added that scientists ht eral blast that would cover some of ! crests. such as We3 e rhaeuser Co..
f Pyroclastic flows are superheated no longet are certain whether the the same tiniberlanr1 that was destroycJ whosr operations north and west of the I
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rivers of bot rock, yas and dust that can " character" of the molten rock under. In the desastaung M.y 18 eruption mountain have been shut dow.n for the
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flow down the in.amtain at speeds ap-neath the mountain has e hanged.
Meanwlale. spokesmen for'the Gil-past Iw o wreks
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